John C. Houbolt, an engineer whose contributions to the U.S. space program were vital to NASA’s
successful moon landing in 1969, has died at 95.

Houbolt died on Tuesday in a nursing home of complications from Parkinson’s disease, his
son-in-law Tucker Withington confirmed on Saturday.

Houbolt was the catalyst in securing the U.S. commitment to the science and engineering theory
that eventually carried the Apollo crew to the moon and back safely.

His efforts in the early 1960s are largely credited with persuading NASA to focus on the launch
of a module carrying a crew from lunar orbit, rather than a rocket from Earth or a spacecraft while
orbiting the planet.

Houbolt argued that a lunar orbit rendezvous not only would be less mechanically and financially
onerous than building a huge rocket to take man to the moon or launching a craft while orbiting the
Earth, but also would be the only option to meet President John F. Kennedy’s challenge before the
end of the decade.

Houbolt started his career with NASA’s predecessor in 1942. He retired in 1985 but was a private
consultant.